Automatic kelly bushing hold-down device

ABSTRACT

A device for automatically interlocking a kelly bushing to a master bushing or other driving element making it possible to raise the kelly and the drill string off the bottom of a well hole without interrupting rotation of the drill string and without risk of breaking the driving connection between the kelly bushing and its power source.

United States Patent Oliver Oct. 21, 1975 AUTOMATIC KELLY BUSHING 1,66l,285 3/1928 Greve 64/235 HOLD D()WN DEVICE 1,758,426 5/1930 Black .1 64/2315 3,386,263 6/1968 Long 64/235 [75] Inventor: Don L. Oliver, Houston, Tex.

[731' Assignee: Cities Service Oil Company, Tulsa, Primary Examiner samuel Scott Okla Assistant ExaminerRandall Heald [22] Fil d; O t 4, 1973 Attorney, Agent, or Firm--Richard S. Strickler [21] App]. No.: 403,355

[44] Published under the Trial Voluntary Protest [57] ABSTRACT Program on January 28, 1975 as document no. B 403 355 A device for automatically interlocking a kelly bushing to a master bushing or other driving element mak- 52 U.S. c1 64/235; 175/195 ing it possible to raise the kelly and the drill String Off 51 Int.- c1. F16D 3/06 the bottom of a Well hole Without interrupting rotation [58] Field of Search 64/235, 23.6; 175/195 of the drill String and without risk of breaking the driving connection between the kelly bushing and its [56] References Cited Power Source- UNITED STATES PATENTS 6/1924 Davidson 64/235 7 Claims, 6 Drawing Figures US. Patent I Oct. 21, 1975 Sheet 1 of2 3,913,352

U.S. Patent Oct. 21, 1975 Sheet 2 of2 3,913,352

AUTOMATIC KELLY BUSHING HOLD-DOWN DEVICE BACKGROUND OF THE INVENTION The present invention relates to drilling and relates in particular to deep hole drilling as in the production of gas and oil.

Ordinarily, a drilling rig includes a driving table or rotary powered by a stationary engine through appropriate gearing.

The rotary carries and drives a master bushing, centrally and removably disposed in the rotary and keyed thereto to effect a driving connection.

A kelly bushing is supported centrally by the master bushing and is keyed to the master bushing usually by vertical pins, lugs or other suitable means so as to be separable from the master bushing.

The kelly, having a rectangular or other flat-sided configuration in cross-section, is slidably received within the kelly bushing in well-known fashion.

Since the kelly is secured, as by threads, to the drill pipe or drill string, rotation of the rotary in a predetermined direction drives (rotates) the drill pipe string and the bit in the bottom of the well hole.

The power train leading from the stationary engine to the rotary, the main bushing, the kelly bushing and finally to the kelly drives the drill string.

Since the kelly makes a sliding fit with its bushing, the kelly is free to drop or move downwardly toward the bottom of the well hole as the drilling operation progresses.

Theoretically, the kelly can be raised or moved upwardly relative to its mating bushing; however, in practice this is not the case in all situations as will be explained in more detail hereinafter.

While conducting a drilling operation and during the course of rotating the drill bit in .the bottom of the hole, its frequently desirable to lift the drill string and the drill bit off the bottom of the hole while maintaining rotational speed of the rotary, the kelly and other intermediate driving members.

Friction between the kelly and the kelly bushing is very high because of the high torque exerted upon the kelly by its bushing. The level of friction is so high that if any operator undertakes to lift the drill string while rotating the drill, friction between the kelly and its bushing causes the kelly bushing to ride up with the kelly to the point where the kelly bushing becomes disengaged from the master bushing.

This occurrence, i.e., uncoupling of the kelly bushing from the master bushing, creates a catastrophic back lash in the drill string as the twisting torque of the drill string is suddenly released.

Consequently, whenever an operator is faced with a requirement to pick up while continuing to rotate the drill string, he must be certain that the kelly, during the course of its upward movement, does not carry with it the kelly bushing resulting in breaking its driving connection with the master bushing.

Therefore, in this situation, the operator is forced to use complicated and cumbersome procedures such as chaining or bolting the kelly bushing to its drive member.

Thus, it is a feature of this invention to provide a coupling between the kelly bushing and the master bushing which is operable centrifugally to maintain the coupling during rotating of the drill string and which automatically uncouples when the drill string is at rest.

A further feature of the invention is the provision of a series of centrifugally operable couplings releasably connecting the kelly bushing to the master bushing and the master bushing to the rotary.

In this alternative embodiment of the invention the kelly bushing is coupled to the master bushing and the master bushing is coupled to the rotary in order to provide additional mass to overcome friction between the kelly and the kelly bushing in situations where friction is extremely high and the operator requires additional assurance that the power train remain intact.

SUMMARY OF THE INVENTION A representative embodiment of the invention may comprise a driven rotary table, a master bushing keyed to the table, a kelly bushing separably keyed to the drive bushing and moveable lock means carried by the kelly bushing operable to engage mating lug means in the drive bushing, said lock means being moveable from a first position in which the lock means are free of said lug means and the kelly bushing is separable from the drive bushing, to a second position in which said lock means engages said lug means in response to contrifugal force .whereby the kelly bushing is coupled to the master bushing.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention will become more apparent from an examination of the succeeding specification when read in conjunction with the appended drawings, in which;

FIG. 1 is a prospective view of a typical rotary drill rig as viewed at the platform.

FIG. 2 is a section view of a portion of FIG. 1.

FIG. 3 shows the kelly bushing uncoupled and separated from its mating master bushing.

FIG. 4 shows the kelly bushing and the master bushing in the coupled position in that the centrifugal force created by rotation causes the moveable lock means to swing to an operable or locking position.

FIG. 5 is an enlarged view of a portion of FIG. 4 to show details of the lock means and the lug means and FIG. 6 is a side view of a portion of FIG. 5 as viewed from the left to show further details of the coupling structure.

DETAILED DESCRIPTION OF THE INVENTION Referring now in detail to the drawings, the letter A denotes a kelly slidably received in kelly bushing B in turn keyed to master bushing C which makes a driving connection with rotary D, all arranged in the usual and customary fashion on a typical well hole platform.

Referring to FIGS. 3 and 4, kelly A is shown slidably received in kelly bushing 10 having aligning pins 11-11 operable to engage mating recesses 12-12 in master bushing 13. Bushing 10 is formed with a frustroconic section or nose 14 received in a mating cavity 16 of master bushing 13 which facilitates the alignment of pins 11-11 when kelly bushing 10 is moved from the position of FIG. 3 to the position of FIG. 4.

Note that kelly bushing 10 is formed with a pair of pivotally mounted, free swinging lock means, hooks or dogs 17-17 operable to engage mating pins or lug means 18-18 fixed to master bushing 13.

In the disclosed embodiment of the invention there are two dogs 17-17. Obviously, additional dogs may be utilized as considerations of mechanical design and size of drill rig may dictate.

The dogs l717 are shown in FIG. 3 in their normal or first position so that when the drill rig is at rest and the kelly bushing 10 is lowered to the master bushing and keyed thereto by the cooperation of pins l11l and corresponding recesses 1212, the dogs 17 hang free and uncoupled as shown in the dotted line position labeled 17al7a in FIG. 4.

Rotation of the table 19 drives master bushing 13 in turn driving kelly bushing 10 and ultimately the kelly A in a predetermined direction and by virture of the fact that all these elements are keyed to one another in a well known manner. 1

Upon the occurrence of rotation of the drill string, centrifugal force is operable to cause dogs 17-17 to move or swing outwardly from the position designated by l7al7a in FIG. 4 to the position designated by l7b17b with the result that a locking or coupling connection is effected with pins 1818 carried by master bushing 13. t

In this fashion the kelly bushing 10 is positively connected or coupled to the master bushing creating a very substantial mass.

Thus, the operator, during the course of drilling, is free to lift the drill string off the bottom of the wellhole without interrupting rotation of the drill with assurance that the combined mass of the coupled kelly bushing and master bushing will overcome friction between the kelly bushing and the kelly which would otherwise tend to cause the kelly bushing to pick up and break its connection with the master bushing as shown in FIG. 3.

FIGS. 5 and 6 show details of a representative embodiment of a typical lock means or dog 17 pivotally supported by a hinge pin 21 fixed to kelly bushing 10. Dog 17 is formed with a lip 22 operable to engage and make releasable contact with a pin 23 fixed to master bushing 13.

' In the event additional mass is necessary in order to provide further assurance that there will be no separation or break in the power train including the rotary, the master bushing and the kelly bushing, it is entirely within the scope and principles of the present invention to utilize a second set of lock means or dogs l7l7 to make a releasable and centrifugally operable connection between the master bushing and the rotary table.

In this embodiment of the invention the mass overcoming friction between the kelly and the kelly bushing would include the combined mass of the kelly bushing, the master bushing and the rotary table.

In some extreme cases the rotary table can be secured to the overall rig to provide an even greater mass comprising the kelly bushing, the master bushing, the rotary table and the table anchor.

It is anticipated that wide variety of embodiments of the present invention may be devised without departing from the spirt and scopethereof.

What is claimed is: v

1. In a drill rig an automatic apparatus for maintaining a driving connection between a kelly and its rotary table effective to permit lifting the drill string and bit off the bottom of a well hole while rotating the drill string comprising a driven rotary member, a kelly bushing separably keyed to the rotary member and movable lock means carried by the kelly bushing operable in response to centrifugalforce to make a releasable connection with lug means carried by said rotary member and operable in response to gravity to release said connection when the drill string isat rest.

2. The apparatus of claim 1 in which the driving connection between the kelly bushing and the rotary member includes a master bushing. i

3. The apparatus of claim 1 in which the driving connection-between the kelly bushing and the rotary table includes a master bushing having a plurality of lug means which cooperate with mating lock means of said kelly bushing. I

5. An automatic apparatus formaintaining a driving connection between a kelly and its power means comprising a driven rotary power means, a kelly bushing keyed to and driven by the power means, said kelly bushing being movable axially of said power means and coupling means carried by the kelly bushing and operable in response to centrifugal force arising from kelly bushing rotation to engage mating lugs in said power means effective to preclude said axial motion, said coupling means being operable to fall freeof said lugs when the drill string is at rest.

6. In a drill rig an automatic apparatus for maintaining a driving connection between a kelly and its rotary table effective to permit rotation of the drill pipe while simultaneously lifting the drill pipe string and bit'off the bottom comprising a driven rotary table, a drive bushing keyed to the table, a kelly bushing keyed to but separable from the drive bushing and a plurality of hooks each having a lip carried by the kelly bushing operable to engage mating pins in said drive bushing in response to centrifugal force generated by rotation of the kelly bushing whereby the kelly bushing and the drive bushing are locked or coupled together, said hooks being operable to fall free of said pins in response to gravity when the drill string is at rest. I

7.' The apparatus of claim 6 in which the drive bushing'is releasably coupled to the rotary table and the rotary table is anchored to the drill rig. 

1. In a drill rig an automatic apparatus for maintaining a driving connection between a kelly and its rotary table effective to permit lifting the drill string and bit off the bottom of a well hole while rotating the drill string comprising a driven rotary member, a kelly bushing separably keyed to the rotary member and movable lock means carried by the kelly bushing operable in response to centrifugal force to make a releasable connection with lug means carried by said rotary member and operable in response to gravity to release said connection when the drill string is at rest.
 2. The apparatus of claim 1 in which the driving connection between the kelly bushing and the rotary member includes a master bushing.
 3. The apparatus of claim 1 in which the driving connection between the kelly bushing and the rotary table includes a master bushing having a plurality of lug means which cooperate with mating lock means of said kelly bushing.
 4. The apparatus of claim 1 in which the driving connection between the kelly bushing and the rotary member includes a master bushing and the kelly bushing carries a first set of lock means cooperating with mating lug means carried by the master bushing and the master bushing carries a second set of lock means cooperating with mating lug means of said rotating member whereby the kelly bushing, master bushing and rotary are all releasably coupled together upon rotation of the rig.
 5. An automatic apparatus for maintaining a driving connection between a kelly and its power means comprising a driven rotary power means, a kelly bushing keyed to and driven by the power means, said kelly bushing being movable axially of said power means and coupling means carried by the kelly bushing and operable in response to centrifugal force arising frOm kelly bushing rotation to engage mating lugs in said power means effective to preclude said axial motion, said coupling means being operable to fall free of said lugs when the drill string is at rest.
 6. In a drill rig an automatic apparatus for maintaining a driving connection between a kelly and its rotary table effective to permit rotation of the drill pipe while simultaneously lifting the drill pipe string and bit off the bottom comprising a driven rotary table, a drive bushing keyed to the table, a kelly bushing keyed to but separable from the drive bushing and a plurality of hooks each having a lip carried by the kelly bushing operable to engage mating pins in said drive bushing in response to centrifugal force generated by rotation of the kelly bushing whereby the kelly bushing and the drive bushing are locked or coupled together, said hooks being operable to fall free of said pins in response to gravity when the drill string is at rest.
 7. The apparatus of claim 6 in which the drive bushing is releasably coupled to the rotary table and the rotary table is anchored to the drill rig. 